National Weather Service officials have issued a winter storm watch for the mountains of Los Angeles County as rain, high winds, unseasonably cold temperatures and snowfall are expected to hit the region today, forecasters said.

NWS forecasters said the storm will likely move in this afternoon, will extend into the evening, and will possibly last into Wednesday.

“This is just a big surge of arctic air coming on a jet stream on steroids coming straight at us,” he said. “You get one of these every five years. It’s what I call the polar express.”

The bulk of the rain from this storm should begin to falling on Southern California on Monday, Patzert said. The amount of rainfall depends on whether the “tremendous cold front” travels over the ocean on its way here, he said.

Snow levels are expected to start today at between 5,500 and 6,500 feet before falling to between 3,500 and 4,500 feet tonight and Sunday, according to forecasters.

“Snow levels are expected to be even lower by Tuesday night into Wednesday, possibly as low as 2,000 to 2,500 feet in any heavier showers,” according to the NWS’ advisory.

“Wintry” driving conditions in the mountains could last until Wednesday, especially above 3,500 feet. Interstate 5 from the Grapevine to Santa Clarita will likely be impacted by snowfall at times during the period.

Patzert noted that the storm will bring much-needed rain to an area that’s had eight consecutive dry months.

“There’s a lot of good news here,” he said. “We need the rain, we need the snow cap.”

Firefighters who have been battling dry conditions should also welcome the precipitation, and surf should be up as well as a result of the storm.

“The only one that’s going to be bummed out is the Highway Patrol,” Patzert said.